Serotonin (5-HT) receptors have been subdivided into seven main families, of which the 5-HT.sub.1 receptor family forms a heterogeneous group in which a number of receptors have not yet been properly characterised.
Sumatriptan, an anti-migraine agent, interacts with 5-HT.sub.1 receptors which have been described as being type 5-HT.sub.1B, 5-HT.sub.1D or 5-HT.sub.1-like (Sumner et al., Brit. J. Pharmacol., 105, 603, 1992, Olesen, La Recherche, 23, 160, 1992). The selectivity of sumatriptan for those 5-HT.sub.1B, 5-HT.sub.1D and 5-HT.sub.1-like receptors has been proposed as the main reason for its anti-migraine activity (Macon et al., J. Med. Chem., 37, 2509, 1994), in which selective vasoconstriction of the carotid vascular bed is involved (Saxena et al. T.I.P.S., 10, 200, 1989). Such receptors, which are present in the venous system, are also found in the brain, and their activation or inhibition may be at the origin of certain disorders of the central nervous system (Clitherow et al., J. Med. Chem, 37, 2253, 1994).
The compounds of the present invention have a novel structure by virtue especially of the presence of an aminated side chain that substitutes the heterocyclic nitrogen atom and of a triazole structure that substitutes the aromatic nucleus. That structure, surprisingly, provides the compounds of the invention with a high selectivity for the 5-HT.sub.1B, 5-HT.sub.1D and 5-HT.sub.1-like receptors. They are thus able to be used as a venotonic agent in the treatment of venous insufficiency and of associated disorders, and also in the treatment of migraine and conditions associated with that disorder, "cluster headaches", pain, migraine associated with vascular disorders, and in hypertension, obesity and eating disorders.
The activity of the compounds of the invention has been evaluated in a pharmacological test that measures their potential for contracting the saphenous vein isolated from a dog or rabbit, as described by Humphrey et al. (Br. J. Pharmacol., 94, 1123, 1988).